While aviation is an important contributor to climate change and other environmental problems, introducing battery-electric aircraft can potentially reduce these environmental impacts.
The first battery-electric electric aircraft are already in operation and are mainly small planes used for pilot training and short flights in the immediate area.
Researchers at Chalmers University of Technology have performed a life cycle assessment on these planes, directly compared to a commercial, fossil-fuelled plane.
“In the short-term future, battery-electric aircraft will probably mostly be used for shorter distances, such as what in Norway is called ‘fjord-hopping’, meaning shorter flights between deep fjords,” explained Rickard Arvidsson, lead author of the study.
“The study shows that this aircraft has the potential to significantly reduce environmental impacts of aviation.”
The study, ‘Life cycle assessment of a two-seater all-electric aircraft,’ is published in The International Journal of Life Cycle Assessment.
What did the research discover about battery-electric aircraft?
The team examined a commercially available battery-electric aircraft with two seats called the ‘Pipistrel Alpha Electro’ in the life cycle assessment.
The same aircraft is also available as a fossil fuel-powered model, enabling the researchers to compare directly.
The researchers investigated the entire impact of each aircraft from raw material extraction to end of life – with a functional unit of one hour flight time. Data and records from the aircraft manufacturer informed much of the study.
A wide range of impact categories was considered, with a focus on global warming from greenhouse gas emissions, mineral resource scarcity from the use of rare minerals, particulate matter formation from particle emissions, acidification from acidic emissions, and ground-level ozone formation from emissions of nitrogen oxides and hydrocarbons.
Arvidsson said: “The key take-home from this study is that small battery-electric aircraft can have up to 60% lower climate impact than equivalent fossil-fuelled aircraft.
“However, there is a trade-off regarding mineral resource scarcity – about 50% more even in the most favourable scenario, mainly due to rare metals in the batteries of the electric aircraft.”
The benefits of electric planes are released over time
As with electric cars, the battery-electric aircraft is comparatively worse from a climate point of view when the plane is brand new since the production of the battery consumes a lot of energy and resources.
However, the relative impact decreases as the electric plane is used and its benefits are realised. The longer the electric plane is used, the better it becomes for the environment, and eventually, a ‘break-even’ point is reached.
After approximately 1,000 flight hours, the battery-electric aircraft overtakes the fossil fuel aircraft in terms of less climate impact, after which the electric aircraft is better for the environment.
This is measured in kg CO2 eq/h – carbon dioxide equivalents per flight hour and is true under optimal conditions where green energy is used.
Therefore, all use after becomes a climate benefit compared to the conventional aircraft. The estimated lifespan of the aircraft is at least 4,000 hours, or four times as long as the break-even time.
New and better batteries are needed for a greener future
In the study, the researchers discuss the further development of batteries as a major step towards reduced lifecycle impacts of battery-electric aircraft.
“The lifetime of the lithium-ion batteries would have to be about twice as long for the mineral resource scarcity to be about the same for the electric aeroplane and the fossil-fuel aircraft,” stated Anders Nordelöf, one of the study’s co-authors.
Already, the manufacturer of the aircraft model has managed to extend the life of the batteries as much as three times.
New battery technologies could further improve both climate impacts and mineral resource scarcity.
Arvidsson concluded: “There is a constant development of lithium-ion batteries that can improve the environmental performance of the battery-electric aircraft and make it relatively even more preferable than the fossil-fuelled one.
“There are also new battery technologies that could be developed and be applicable to electric aircraft in a longer time perspective, such as lithium-sulfur batteries, although these are still in an early phase of technology development.”
